Need info on Yanmar 3TNA72

[bwc]

Good morning. Can someone answer what model Yanmar tractor uses this engine? I have a JD 455 garden tractor with this engine and was curious about the engines reputation for reliability etc. I am experiencing a knock in the engine and have been told by my JD dealer that it is a fuel related noise. The high pressure fuel lines were opened to allow any air out if any but the knocking is still there especially at WOT. It will go away for a second if you suddenly back off the throttle. All lines are tight, no leaks, fuel filter new and fuel additive is being used. Thanks.

Brian

 

[jamtrac2002]

Since the problem is only occurring at wide open throttle, I would suspect a timing problem. Either valve clearance timing or fuel injection timing.

 

[lens12]

The JD engines are spec engines built to JD's specifications. The 3TNA72 is probably similar to the YM186 & YM187, but not identical. If the lines were opened , there still may be a little air in the injector lines. If this is the cause it will work its way out.

 

[cfoxmd]

John Deere puts out a manual for the 3TN and 4TN yanmar engines. The Component Technical Manual is labelled as volume CTM3 and includes your engine. This includes variety of specifications and procedures for the engine. It doesn't really discuss troubleshooting though. There also seems to be a service manual by Deere labelled JD-CTM3 (which is listed at 720 pages and therefore must be different from the CTM3 which I have a copy of. The link is Link that sells the manual for $99.

 

[bwc]

Thank you gentlemen for your information. The "knocking" has subsided and everyting is running as per normal. Have a great day and play safe.

Brian

 

[jamtrac2002]

Since the knocking has subsided and then re-occurred a couple times, I would suspect the fuel you are using. Have you tried a fuel additive or a cetane booster? A good fuel additive would clean up your injectors, try to get one that contains a cetane booster, or add that seperately and see if that doesn't make a difference.

 

[mic247]

Komatsu used this same engine 3TNA72 Yanmar, in their pc05-5 mini excavators but tagged them with a different label 3D72-2B. This made it a nightmare for those of us who were looking for parts as it took two weeks of contacting Yanmar and Komatsu dealers to finaly get this cross referenced. Apparently these are commonly used in John Deeres and a few other machines. If you can find any manuals or parts suppliers for this engine, I would love to have the info as I am still trying to find someone with parts.